1. Field of the Invention
The present invention is generally related to a grain bin structure, and, more particularly, to a grain bin having side walls containing integral vertical stiffeners which also function as conduits for dispersing air about the interior surface of the bin.
2. Description of the Related Art
In the past, several grain bin structures have been proposed, such as those illustrated in the following U.S. Pat. Nos.: 4,885,985 (Pollock); 4,319,411 (Steffen); 4,009,520 (Sukup); 3,608,204 (Ashby); and 3,531,874 (Sukup).
These conventional grain bins include a tubular side wall structure having a plurality of horizontally aligned corrugations thereabout. The bin rests upon a cement foundation. A raised perforated floor may be built within the bin and supported by vertical columns to form an air pressure chamber below the perforated floor. A blower directs air into the chamber to maintain a desired pressure therein. Pressurized air escapes upward through the perforations and upward through the grain to be discharged through vents located in the bin roof. This air flow process effects grain drying.
The '874 patent to Sukup discloses a device for drying grain which includes a blower heater unit which directs air under the perforated floor of the bin. Additionally, a plurality of physically separate conduits are attached along the inside wall of the bin. The conduits or tubes are disposed vertically to promote air circulation at the periphery of the bin. Each tube is secured to the wall via braces. Multiple holes in each tube allow air to flow therefrom. The '520 patent to Sukup discloses a grain drying system which similarly uses a plurality of physically separate tubes extending vertically along the walls of the bin to direct air flow into the bin. In the '520 Sukup patent, the tubes are formed with a triangular cross-section and include holes along opposite sides thereof to direct the air flow about the perimeter of the bin.
The patent to Pollock discloses a grain bin arrangement which provides air flow to areas along the levels of the grain. Pollock's system includes a plurality of tubes or conduits extending vertically along the walls of the bin, with each conduit having air outlets. In addition, an air float is provided in each tube and slides therealong to direct the air into the grain and prevent the air from traveling along the tubes to a position above the level of the grain. The patent to Steffen discloses a grain bin constructed with aspirating panels about the exterior to admit air to freely flow through the walls of the grain bin. The patent to Ashby discloses a vessel for storing grain which contains a plurality of ribs extending about the exterior of the sphere. The ribs may form conduits and have spaced perforations along the length thereof. The ribs provide air flow along the inner casing of the bin.
However, these conventional grain bin systems have met with limited success. First, the horizontal corrugations hinder air flow upward along the interior surface of the side walls as air attempts to travel vertically along these corrugations. The air is unable to follow the wave-like contour of the corrugations and hence without Sukup's and Pollack's internal conduits, air does not flow through grain stored within the valleys of the corrugations, nor does air flow through the grain immediately adjacent the side wall. The absence of air flow immediately adjacent the side walls causes the grain in these regions to spoil since its moisture content is not reduced through drying. Additionally, often condensation collects upon the interior surface of the bin wall, further exposing the grain to moisture.
While Sukup's and Pollack's systems attempt to address this problem, they do not direct the air into the horizonal corrugations. The air outlet ports in the vertical conduits are displaced radially inward from the horizonal corrugations and as such the conduits do not necessarily direct the air along the corrugations. Instead, air from the vertical conduits is direct into the grain and disbursed proximate the conduit. Thus the conventional vertical conduits have not effectively achieved true air flow along the entire interior perimeter of the bin.
Moreover, these conventional systems have experienced additional problems. For instance, Sukup's and Pollock's vertically disposed conduits are secured to the interior of the bin with brackets. The conduits and brackets are disposed within the interior of the innermost ridges surface of the side wall formed by the innermost peaks of the corrugations. Conventional bins typically utilize an auger assembly located within the bin to stir the grain therein. This auger travels about the circumference of the bin and moves radially inward and outward as it pulls the grain upward to stir the entire perimeter region. Pollock's and Sukup's systems prevent the auger from functioning immediately adjacent the interior surface of the bin. Instead, the auger must be limited to a range of motion which does not interfere with the conduits. Hence, no grain circulation is achieved proximate the side walls and this grain must be exclusively dried through air circulation. Further, quite often the stirring augers accidentally become misaligned and move too far outward and engage the conduits. Thus Pollock's and Sukup's systems are quite sensitive to auger misalignments which typically rip the conduits loose from the bin and result in substantial damage to the overall drying system.
Moreover, conventional grain bins have experienced failures within the integrity of the side walls. These failures occur when the side walls experience undue down loading (i.e., downward forces caused by the grain load and by the weight of the upper portion of the bin, along with the downward forces created by the stirring machinery which continuously lifts grain and induces a downward force upon its support structure located at the top of the bin). When failures occur, typically the corrugations "roll downward" or buckle. To overcome this problem, conventional bins utilize a thick side wall structure formed from a large gauge material. The necessity for thicker side walls increases the bin's overall expense. Pollack's and Sukup's vertical conduits offer little vertical support.
The patent to Kramer proposes a grain bin structure utilizing horizontal and vertical corrugations. However, Kramer's system is unduly complex and expensive to manufacture and provides limited additional structural support.
Finally, within conventional grain bin, each side wall sheet used to form the bin must be manufactured with a specific curve formed therein conforming to the diameter of the bin within which the sheet will be used. Hence, a bin having a 24 foot diameter requires side wall sheets to be formed (or "rolled") with one curve, while a bin having a larger diameter requires sheets to be formed with a second lesser curve. Accordingly, manufacturers and dealers are required to maintain separate inventories of side wall sheets for each size of bin. This practice substantially increased the inventory requirements and was undesirable. In addition, when manufacturing conventional wall sheets, the sheet must be passed through a roller assembly to provide the desired curve therein. The roller manufacturing step increases the manufacturing cost and is also undesirable.
Hence, a need remains within the industry for an improved grain bin with enhanced air flow and structural integrity. It is an object of the present invention to meet these needs.